Question

Question #4014f

Answer 1

Si-30 = 29.9344 amu, 3.2%

Explanation:

The way to calculate isotopic mass is with this formula:

`"molar mass"=sum("amu"*"% abundance")`, so we can start plugging in some numbers using the molar mass of Silicon from the periodic table and the numbers provided:

`28.0855=(27.9769*0.922)+(28.9765*0.046)+(x*0.032)`

I got 0.032 from subtracting `0.922+0.046` from 1 (because % abundance needs to add up to 100%).

Now that we have the numbers plugged in, we solve algebraically:

Step 1: Simplify right side

`28.0855=27.1276+(x*0.032)`

Step 2: Subtract 27.1276 from both sides

`0.9579=x*0.032`

Step 3: Divide by 0.032 on both sides to get isotopic mass of Si-30

`29.9344=x`

Hope this helped!